Flameproof cellulose acetate fabrics



March 19, 1963 R. E. DONALDSON ETAL 3,082,121

FLAMEPROOF CELLULOSE ACETATE FABRICS Filed April 24, 1961 Fi g: 3

RaymondEDonaldson Charlesavhiie INVENTORS United rates This invention relates to the treatment of carpets produced from cellulose acetate fibers and yarns to give this type of fabric flame-retardant properties.

Heretofore, many treatments of various kinds of fabrics have been proposed for rendering such fabrics resistant to burning. For example, it has been proposed to fiameproof or render resistant to burning cotton or viscose fabrics by depositing on such fabric various water soluble salts from their aqueous solutions, but it has been found that these agents are not effective in iiameproofing cellulose acetate carpet materials at low add-ons such as 1-3% of the fiameretardant agent based on the weight of the lfabric or fiber. When it has been attempted to employ lhigher add-ons of the order of 5-25%, `for example, the so-treated fabric has been found to have an excessively harsh hand or the carpet is stiff and boardy and has a poor appearance. It has also been found that add-ons of this amount of t-he dame-retardant agent degrades the physical properties of the carpet. Many'water soluble materials such as sodium tetraborate, sodium phosphate, ammonium phosphate, ammonium sulfamate, sodium carbonate, potassium bicarbonate, and many others have been proposed for flameproofing cotton and viscose but none of these materials have been found to be effective in fiameproofing cellulose acetate carpets.

In addition to the agents referred to above, a number of other inorganic salts have been shown to have some efficacy as fiameproofing agents when applied to various textile fibers and fabrics but in the course of the investigative work' which led up to the present invention we have not found that any of these materials are effective in fiameproofing cellulose acetate carpets at commerciallly acceptable add-ons, that is, an amount of the agent sufficient to contribute flame-retarding properties but at the same time not give rise to undesirable physical propertiessuch as poor or harsh hand, stiffness or boardiness, or poor appearance of the carpet fibers.

By the terms fiame retardant or flameproofing agent as used herein and in the appended claims, we refer to an agent which will render the fiber or fabric material to which it is applied self extinguishing, that is, not supporting combustion after having been exposed to an open ame for 30 seconds. By the same token, when We refer herein and in the appended claims to a flame resistan or flameproofed fabric, lwe refer to a fabric which has this property of being self extinguishing or not supporting combustion after exposure to an open flamle for 30 seconds.

This invention accordingly has as an object the iiameproofing of fibersand fabrics, particularly those composednof orcontaining cellulose acetate fibers.

Anotherobject is torprovide a means of flarneproong a rug fabric in which the fibers constituting the pile of the rug consist of or contain a high proportion of cellulose acetate fibers.

Another object is to provide a process of ameproofing a rug fabric in which the fibers constituting the pile of the rug consist of or contain a proportion of celluiose acetate fibers by treating the fabric with a-n improved and novel fiarneproofing agent.

Another object is to provide a process of flameproofing arug `construction in which the pile consists of or contains cellulose acetate fibers by an expedient in which arent rice the flameproofing agent is incorporated in and held the backing binder of the rug and available for later de] osition on the rug fibers in a simple and effective manne Another object is to provide a flameproof or flam resistant rug fabric in which the fibers constituting tl pile of the rug consists of or contains a high proportie of cellulose acetate fibers with a very 10W add-on 1 flameproofing agent.

Another object is to provide a means of flameproofir a rug construction in which the pile is composed of ce lulose acetate fibers without adversely affecting the har of the fabric, rendering it stiff and boardy or adverse affecting the appearance of the bers.

Another object is to provide a means of flameproofir a rug construction in which the pile is composed of ce lulose acetate fibers tufted into a jute back which will n4 adversely aect the cellulose acetate rug fibers and wi not cause chemical deterioration of the jute back or tl carpet fiber.

Another object is to provide an improved flame-Tesis ant or flameproofed rug construction in which the pi consists of or contains a substantial proportion of fibe of cellulose acetate.

Other objects will appear hereinafter.

These objects are accomplished by the following inver tion which, in its broader aspects, comprises depositir on or in a rug construction consisting of or containir cellulose acetate fibers a group I alkali metal format According to one embodiment of the invention, tl carpet is simply treated with an aqueous solution of tl alkali metal formate under such conditions that, upc drying of the treated carpet, the alkali metal formate deposited on the carpet fiber preferably in an amou; Icorresponding to 1-2%, based on the weight of tl treated carpet fibers. In this embodiment, for exampl a l0-40% solution of an alkali metal formate such sodium formate, potassium formate or lithium format may be simply sprayed on the fabric and the Water r moved by evaporation or drying, leaving a surface d posit of the formate clinging to the fibers. In aneth embodiment of the invention, the alkali metal forma may be mixed with the latex or other resinous bindt commonly employed as the back size coating which locl the pile loops into the base fabric, which is usually jut The alkali metal formate in this mixture may constitu from 1 to 25% by weight of total solids of the compos tion, although we prefer to employ an amount of tl formate corresponding to 10- to 14% of the total soli( of the back sizing composition. After the back siZ/e coa ing is applied and properly hardened, the rug fabric mz then simply be sprayed with water 'which leaches a po tion of the alkali -metal formate out of the backing layi and deposits it in the form of a thin film of alkali met formate `solution on the surface of the bers of the ru While the amount of the alkali rnetal formate thus d posited is not critical it is believed that about 1%, bas on the weight of the carpet fibers, is thus deposited. l any event, upon evaporation of the water a deposit i the solid alkali metal formate is left on the fiber surfw to produce the desired flame resistant effect. It shou be noted at this point that one of the particular featurl of novelty of our invention is the fact that a carpet iiarn proofed in accordance therewith may be washed numbe of times without losing its iiameproof character. This because the backsize coating in effect provides a reserve of fiameproofing agent, namely, the alkali metal format 4 which may be brought to the surface of the carpet libe FIGURE 2 is a view showing the carpet construction f FIGURE 1 in detail for a small portion of the carpet.

FIGURE 3 is a schematic illustration showing the iethod of depositing a latex layer containing an alkali Letal formate on the back of a carpet construction such s shown in FIGURES 1 and 2.

Referring to FIGURES 1 and 2 ythe numeral 1 desigates a carpet backing fabric which may be a jute fabric, )r example, onto which has been tufted cellulose acelte carpet yarns 2 in the manner more specifically illus- 'ated in FIGURE 2. The numeral 3 designates a conuit in the form of a header which supplies an aqueous )lution of an alkali metal formate through a plurality f spray nozzles 4 in the form of a spray onto the surrce of the tufts or loops 2. After spraying the treated arpet is simply dried in a current of warm air, thus leavlg deposited on the tufts or loops of the fabric, particles f solidiedalkali metal formate flameproong agent 5 s shown in FIGURE 2.

Referring to FIGURE 3, the numeral 6 designates a ltex back sizing composition which can be conveniently :mtained in hopper 7 and fed therefrom through delivery rice 8 in a layer 9 on to the fabric backing 1 of a tufted :llulose acetate or similar synthetic ber rug construcon, the thickness of the deposited layer being deteriined by the use of a doctor blade or other equivalent evice (not shown). In this case the alkali metal formate is held in solution or suspension in the deposited latex Lyer. The fabric is treated in a current of Warm air to )lidify the latex backing after which the fabric may be irayed or otherwise treated with water to leach the lkali metal formate from the latex backing into the tufts f the carpet construction and thereby render it flameroof.

In the following examples and description we have set )rth several of the preferred embodiments of our inention but they are included merely for purposes of lustration and not as a limitation thereof.

Example 1 A cellulose acetate carpet is prepared by tufting a celllose acetate carpet yarn into a jute backing. This irpet is back sized with a commercial latex back sizing rmulation having the following composition:

Parts by Weight queous solution of styrene-butadiene latex (50% The back sizing composition is deposited on the back lrface of the rug in any convenient manner, as by runng the rug underneath a hopper from which the back zing composition flows at a controlled rate. The thick- :ss of the coating is determined by the application of a actor blade or a similar device. The deposited coating cured and vulcanized by passing the coated material lrourgh an oven supplied with hot air, the material pass- ,g through the oven at a rate predetermined to elfect le proper curing and vulcanization of the back size iating.

The carpet face is then sprayed with a 10% solution f sodium formate in water and the treated carpet then fied. Under such circumstances a deposit of 2% of )dium formate, based on the Weight of the carpet ber, deposited on the carpet. The treated carpet is then )nditioned to approximately zero percent humidity and sted by subjecting the carpet to an open llame for 30 vconds. The carpet is found to extinguish itself as soon i the flame is removed, while an untreated control carpet of the same material and construction subjected to the same test conditions continued to burn.

Example 2 A cellulose acetate carpet is prepared as described in Example 1 and treated with an aqueous solution of lithium formate which, on evaporation of the water component, left a deposit of 4%, based on the weight of the carpet fiber, of the formate salt. This carpet treated with lithium formate does not burn and is self-extinguishing after the flame is removed.

Example 3 ing composition is prepared having the following ingredients Parts by weight Back sizing composition of Example 1 82.7 Sodium formate 14.0

Sodiu'm-N-methyl-N-oleyltaurate rIhis back sizing composition is deposited on the back surface of the rug and cured as described in Example 1. In a. separate operation the carpet face is sprayed with water and dried by passing the carpet through a chamber heated by air flowing therethrough at a temperature of 120 C. The dry carpet is Ifound to Ibe flamleproofed as measured iby the ameproong test described above.

Example 5 A cellulose acetate carpet is prepared by tufting lofted cellulose acetate yarn into a jute backing. A back sizing composition is prepared having the following ingredients:

Parts by weight Back sizing composition of Example 1 96.0 Potassium formate 1.0

Sodium-N-methyl-N-oleylt aurate 3 .0

This back sizing composition is deposited on the back surface of the rug and cured as described in Example 1. In a separate operation the carpet face is sprayed with water and dried by passing the carpet through a chamber heated by air flowing therethrough at a temperature of 120 C. The dry carpet is found to be ameproofcd as measured by the flameproong test described above.

Example 6 A cellulose aceate carpet is prepared by tufting lofted cellulose acetate yarn into a jute backing. A back sizing composition is prepared having the following ingredients:

Parts by weight Back sizing composition of Example 1 87.0 Lithium formate 10.0

Sodium-N-methyl-N-oleyltaurate 3.0

This back sizing composition is deposited on the back surface of the rug and cured as described in Example 1. In a separate operation the carpet face is sprayed with water and dried by passing the carpet through a chamber heated by air flowing therethrough at a temperature of C. The dry carpet is found to be ilameproofed as measured by the ameproofmg test described above.

Example 7 A carpet prepared as in Example 4 is subjected to a cleaning scour such as is customarily employed in commercial rug cleaning plants. This is done by applying a foaming cleaner such as the product sold under the trade name Artloom Carpet Shampoo, which is a concentrated aqueous detergent or soap solution, to the fiber Surface of the carpet and thereafter scrubbing with brushes. The scoured carpet is allowed to dry. Upon bringing a sample of the treated carpet material to zero humidity and testing for fiammability, it is found that the material does not burn and is self-extinguishing when the initiating fiame is removed, while a carpet of the same material and construction, but lacking the liameproofing formate in the back sizing coating, continues to burn. The scouring operation in this case brings up the formate flameproong agent and deposits it on the surface of the fibers in the manner described above. This process may be repeated many times and the carpet still will retain its flameproof characteristics due to the leaching of the alkali metal formate onto the fibers each time the carpet is wet by water. Example 8 A cellulose acetate carpet is prepared as described in the first two paragraphs of Example l. The carpet face is then sprayed with a 20% solution of potassium formate in water and the treated carpet then dried. Under these conditions a deposit of 2% of potassium formate, based on the weight of the carpet fiber, is deposited on the carpet. Upon applying the flameproofing test described above the carpet is found to extinguish itself as soon as the fiame is removed, while an untreated carpet of the same material and construction subjected to the same testing conditions continued to burn.

In the above examples and in the appended claims We have referred to a latex back sizing composition. By the term latex we include both natural and synthetic latices, including natural rubber latex, styrenelbutadiene copolymers, neoprene, and latices of the acrylic type such as the commercially available polyacrylates, the poly(vinyl) chlorides and similar polymeric flexible film-forming materials. `'It is also to be understood that the latex back sizing composition may contain, as indicated above, various fillers such as titanium dioxide, clays, sulfur, curing accelerators, yoxidation inhibitors, and other such materials commonly used in the art.

As will Abe evident from the above examples and description, our invention has many unexpected and outstanding advantages over the flameproofing practices of the prior art. For example, cellulose acetate carpets may now be flameproofed by the application of very low addons of the iiameproofing material, an especial advantage flowing from this fact being that the cellulose acetate carpet may be flameproofed without the production of boardiness or stiffness of the fabric and without other degradation of the physical properties of the acetate yarn or the backing fabric employed in the carpet construction. Our invention also makes possible the flameproofing of cellulose acetate carpets at an extremely low cost as compared to that involved in the customary methods of flameproofing other fabrics. In this connection it should be particularly pointed out that the flameproofing of cellulose acetate carpet constructions has been impractical or impossible until the advent of the present invention. Thus We have solved a peculiar and long existing problem in the cellulose acetate carpet field. It should also be noted that in that form of our invention in which the flameproofing formate salt is employed as a component of the back sizing composition, there is provided an effective reservoir of the fiameproofing agent which may be brought up onto the fibers as desired by the normal washing or scouring process or by simply wetting the carpet construction and subsequently allowing it to dry. To the best of our knowledge and belief this is an entirely unique method of obtaining the flameproofing of cellulose acetate carpets.

Although the invention has been described in considerable detail with particular reference to certain preferred embodiments thereof, variations and modification: can be effected within the spirit and scope of the invention as described hereinabove, and as defined in the ap` pended claims.

We claim:

1. A iiameproof cellulose acetate carpet in which cel lulose acetate fibers are tufted into a backing fabric, sai( fibers containing on their surface as the liameproofing agent an alkali metal formate.

2. The carpet of claim 1 in which the fiameproofing agent is sodium formate.

3. The carpet of claim l in which the flameproofing agent is potassium formate.

4. The carpet of claim 1 in which the flameproofing agent is lithium formate.

5. The process of flameproofing a carpet composed oi cellulose acetate fibers tufted into a carpet fabric backing which comprises applying to the rug fibers an aqueous solution of an alkali metal formate and thereafter removing the water from 4the applied solution to leave on the fiber: a deposit of the formate.

6. The process of claim 5 -in which the solution is z l to 10% aqueous solution of an alkali metal formate.

7. The process of claim 5 in which the aqueous solutior -is a l to 30% of an alkali metal formate and the water is removed by drying the rug at a temperature below C.

8. The process of claim 5 in which the flameproofing agent is sodium formate.

9. The process of claim 5 in which the flameproofing agent is potassium formate.

10. The process of claim 5 -in which the ameproofing agent is lithium formate.

ll. A lameproof cellulose acetate carpet in which cellulose acetate fibers are tufted into a carpet fabric backing and back sized with a latex back sizing composition containing as a flameproofing agent an alkali metal formate.

*12. A fiameproof cellulose acetate carpet in which cellulose acetate fibers are tufted into a carpet fabric backing and back sized with a latex back sizing composition containing as a fiameproofing agent l to 25%, based on the weight of the total solids of the back size composition, of an alkali metal formate.

13. The carpet of claim l2 in which the alkali metal forma-te is sodium formate.

14. The carpet of claim l2 in which the alkali metal formate is potassium formate.

15. The carpet of claim 12 in which the alkali metal formate is lithium formate.

16. A flameproof cellulose acetate carpet in which cellulose acetate fibers are tufted into a carpet fabric backing and back `sized with a latex `back sizing composition containing as a fiameproofing agent 10 to 14%, based on the weight of the total solids of the back size composition, of an alkali metal formate.

17. The process of fiameproofing a cellulose acetate carpet in which cellulose acetate fibers are tufted into a carpet backing fabric and back sized with a latex back sizing composition containing 1 to 25%, based on weight of the total solid-s of the composition, of an alkali metal formate, which comprises wetting the carpet with Water whereby to leach a portion of the alkali metal formate from the back sizing composition and draw it up and deposit it on the surface of the cellulose acetate fibers.

18. The process of iiameproofing a cellulose acetate carpet in which cellulose acetate fibers are tufted into `a carpet backing fabric and back sized with a latex back sizing composition containing l() to 14%, based on weight of lthe total solids of the composition, of an alkali metal formate, which comprises wetting the carpet with Water whereby to leach a portion of the alkali metal formate from the back sizing composition and draw it up and deposit it on the surface of the cellulose acetate fibers.

No references cited. 

5. THE PROCESS FOR FLAMEPROOFING A CARPET COMPOSED OF CELLULOSE ACETATE FIBERS TUFTED INTO A CARPET FABRIC BACKING WHICH COMPRISES APPLYING TO THE RUG FIBERS AN AQUEOUS SOLUTION OF AN ALKALI METAL FORMATE AND THEREAFTER REMOVING THE WATER FROM THE APPLIED SOLUTION TO LEAVE ON THE FIBERS A DEPOSIT OF THE FORMATE. 